due to the limited scope of his investigation... did not include any in-vitro tests

>- defense mechanism is somehow stimulated through zapping and thus some segment of the immune system, but not the zapper, destroys the invader.

While Dr. Thiel did suggest that, it was due to the limited scope of his investigation. He did not include any in-vitro tests which actually do show that zapping can and does kill many microbes. While a lot depends on the zapper used, the best zappers, like ParaZapper actually do very efficiently kill a wide range of microbes.

Also, you left out one of his very important statements:

"zapping probably did not kill "all bacteria, viruses and parasites"

Again, this is probably because her used the original 30 kHz zappers which have been found to be among the weakest zappers when it comes to killing microbes, as is true for every single frequency zapper that I have tested.

Regardless of what any other zapper may do, it is indisputable that the multi-frequency ParaZapper models can and do kill a wide range of microbes.